Learn the basics and you will be able to throw away the recipe and even make some short cuts, as long as you remember the ratio of roughly equal parts butter and flour to make a roux.

Step one:
In a small pot, gently bring the milk to the boil with the halved onion, 1 bay leaf and peppercorns or whole cloves. Once the milk comes to boiling point, take off the heat and allow the milk to infuse for 5–10 minutes before straining.

Step two:
In a separate pot, melt the butter then stir in the flour until it forms a paste—this is called a roux. Cook out the flour, stirring continuously, for at least a minute.

Step three:

Over a low heat, and whilst continuing to stir, pour in approx. a third of the milk. Once incorporated, slowly stir in remaining milk. By adding the milk slowly you will avoid lumps forming and create a silkier sauce. Continue to stir until the sauce thickens to the desired consistency. Season to taste with salt and white pepper. (If in a hurry you can miss this step. Note: adding cold milk to your roux increases the risk of lumps forming, so ensure you do this slowly.)

Mix it up – add some whole grain mustard to the milk for a mustard sauce, perfect served with corned beef, pork or leeks, or smeared on bread with some ham and cheese for an amazing toasted sandwich.